This invention relates generally to the field of synthetic resinous closures for dispensing containers and the like, and more particularly to an improved form of "tamper evident" closure suitable for selectively closing such containers as tubes of toothpaste and other products which are the subject of tamper proof protection.
In our prior three applications, above identified, the problem involved in molding unitary synthetic resinous closures is extensively discussed, as is a process by which the closure may be molded in such manner as to include projections or rings on an inner surface of the closure which is spread from a free edge thereof to permit removal of the closure without damage to the projection or rings as they part contact with the core of the mold which has an undercut portion to form such projections. Of particular importance is the presence of an internal retaining ring which maintains the cap in engaged condition with the core until the skirt of the closure has been spread radially outward to a degree sufficient to permit disengagement with the undercut portion of the core. This concept has application to a wide range of types of closures and covers, and permits the development of closures which have heretofore been unavailable.
A rapidly expanding need is in the field of closures for collapsible dispensing tubes incorporating the provision of a "tamper evident" cap which will clearly indicate to the purchaser that the tube has been opened subsequent to filling and prior to acquisition by the purchaser. Caps of this type, even if partially captivated, are normally of threaded configuration, fitting rather tightly upon a relatively short correspondingly threaded neck in order to seal the contents of the container. Such caps are usually of relatively short axial length, and have a flat transversely extending end wall which overlies the free edge of the neck with reliance upon the threaded engagement of the neck and skirt or side wall of the cap to effect a sealing action. Such construction does not lend itself to the incorporation of a "tamper proof" or at least "tamper evident" auxiliary sealing means, and as a result resort is often made to a separate overlying sealing means which adds complexity and cost to the packaging. In order to be effective, such means must normally be capable of revealing relative movement between the closure and the container, which is not always possible in the case of a cap engaged by relative rotation.